Impact of insulin treatment in diabetic macular edema therapy in type 2 diabetes

To evaluate the impact of insulin therapy on the outcomes of diabetic macular edema (DME) treatment with vascular endothelial growth factor (VEGF) inhibitors in people with type 2 diabetes.

A retrospective consecutive case series of 95 patients with type 2 diabetes and DME who were treated with anti-VEGF therapy. We examined 2 cohorts: patients taking only oral antidiabetic agents and patients on insulin therapy. The main outcome measures were change in visual acuity and change in central subfield macular thickness measured by spectral-domain optical coherence tomography. The additional variables analyzed included glycated hemoglobin (A1C), creatinine, blood pressure and body mass index and their correlations with clinical findings.

Both groups had a statistically significant improvement in visual acuity (oral antidiabetic agents group: 20/61 to 20/49, p=0.003; insulin therapy group: 20/76 to 20/56, p=0.005). There was no difference between groups at initial or 12-month examination (p=0.239 and p=0.489, respectively). From an anatomic standpoint, central subfield macular thickness also improved significantly in both groups: from 454.7 μm to 354.9 μm (p<0.001) in the oral antidiabetic agents group and from 471.5 μm to 368.4 μm (p<0.001) in the insulin therapy group. Again, there was no significant difference between groups at initial or 12-month follow-up examinations (p=0.586 and p=0.591, respectively). Mean A1C levels remained relatively stable during the follow up in both groups.

Anti-VEGF therapy is a useful treatment for DME. This study suggests that chronic insulin therapy, compared with oral antidiabetic agents, does not modify the anatomic or functional effectiveness of DME treatment.